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ABRA: Teleporting Fine-Tuned Knowledge Across Domains for Open-Vocabulary Object Detection

Mattia Bernardi, Chiara Cappellino, Matteo Mosconi, Enver Sangineto, Angelo Porrello, Simone Calderara

Abstract

Although recent Open-Vocabulary Object Detection architectures, such as Grounding DINO, demonstrate strong zero-shot capabilities, their performance degrades significantly under domain shifts. Moreover, many domains of practical interest, such as nighttime or foggy scenes, lack large annotated datasets, preventing direct fine-tuning. In this paper, we introduce Aligned Basis Relocation for Adaptation(ABRA), a method that transfers class-specific detection knowledge from a labeled source domain to a target domain where no training images containing these classes are accessible. ABRA formulates this adaptation as a geometric transport problem in the weight space of a pretrained detector, aligning source and target domain experts to transport class-specific knowledge. Extensive experiments across challenging domain shifts demonstrate that ABRA successfully teleports class-level specialization under multiple adverse conditions. Our code will be made public upon acceptance.

ABRA: Teleporting Fine-Tuned Knowledge Across Domains for Open-Vocabulary Object Detection

Abstract

Although recent Open-Vocabulary Object Detection architectures, such as Grounding DINO, demonstrate strong zero-shot capabilities, their performance degrades significantly under domain shifts. Moreover, many domains of practical interest, such as nighttime or foggy scenes, lack large annotated datasets, preventing direct fine-tuning. In this paper, we introduce Aligned Basis Relocation for Adaptation(ABRA), a method that transfers class-specific detection knowledge from a labeled source domain to a target domain where no training images containing these classes are accessible. ABRA formulates this adaptation as a geometric transport problem in the weight space of a pretrained detector, aligning source and target domain experts to transport class-specific knowledge. Extensive experiments across challenging domain shifts demonstrate that ABRA successfully teleports class-level specialization under multiple adverse conditions. Our code will be made public upon acceptance.
Paper Structure (15 sections, 19 equations, 5 figures, 5 tables, 1 algorithm)

This paper contains 15 sections, 19 equations, 5 figures, 5 tables, 1 algorithm.

Figures (5)

  • Figure 1: Goal. Transfer class-specific knowledge from the source domain to unavailable target classes without access to target-domain data.
  • Figure 2: Overview of the transfer pipeline. Starting from domain experts obtained through Objectification, class-specific residuals learned via SVFT in the source domain are analytically transported to unseen target domains.
  • Figure 3: Objectification. Each domain is fine-tuned using a unified "object" label to capture domain appearance.
  • Figure 4: Effect of specialization on Cityscapes. Dedicating one expert per class (ABRA) yields higher AP$_{50}$ than using a single unified expert (Merge).
  • Figure 5: Few-shot transfer evaluation. Cityscapes comparison (mAP) between the standard pretrained backbone ($\theta_0$) and ABRA across varying numbers of shots.